Energy dissipators principally involve hydraulic shock absorbers which utilize a fluid and thus are subject to fluid leaks which disable the usefulness of the devices or they involve friction washer shock absorbers which are typically nonadjustable without a reconstruction and which cannot be automatically reset.
The present invention concerns itself with an automatically resetable energy dissipator with an all metal construction.
The following represents the available prior art patents.
U.S. Pat. No. 4,457,741 issued to H. W. Hoeptner on Jul 3, 1984. This patent discloses a chain tensioner device which has a configuration somewhat similar in appearance to the present invention but is totally different in function and operation. The Hoeptner device is concerned with forcing a plunger by spring means in a body in one direction to transmit a chain tensioning force to a chain. An automatic locking device prevents retraction of the plunger into the body. The function and purpose of the device is to act as a reverse lock and prevent motion in one direction while permitting spring forced motion in the other direction. The device does not relate to any energy absorbing capability or function. The Hoeptner device uses a steep ramp angle of 15.degree. to 25.degree. which is above the typical locking taper angle in mechanical devices.
U.S. Pat. No. 3,820,634 issued to Lloyd R. Poe on Jun. 28, 1974. Poe discloses a shock resisting device which uses one or more indenting elements which engage and move along an elastomeric member to cause progressive deformation of the elastomer member and attendant energy absorption. It is the deformation of the elastomeric sleeve which provides the energy absorption capability. In the Poe device, a high number of repeated cycles could cause wear to the elastomeric sleeve.
U.S. Pat. No. 4,010,940 issued to A. Freyler on Mar. 8, 1977. This telescopic shock absorber has a number of compressible spheres located between expansion and centering rings as well as a pair of slanting break discs for absorbing shock. The compressible spheres are made of rubber or another plastic material.
U.S. Pat. No. 3,866,724 issued to H. S. Hollnatel on Feb. 18, 1975. This energy absorbing device is a frictional shock absorber which has a non linear relationship between the shock force and resistance to displacements. A resilient actuator member coacts with a wedge member to urge friction pads into engagement with the walls of a housing member. The outward displacement of the friction pads increases as a function of movement of the wedge member.
U.S. Pat. No. 3,127,788 issued to J. E. Martens on Apr. 7, 1964 discloses only a position retaining device which includes a shock absorber.
U.S. Pat. No. 3,382,955 issued to G. P. Deyerling on May 14, 1968. This patent discloses the stroking of the impact rod actuates friction pads which move outwardly so that the pads slide along the inner radius wall of the housing. This device utilizes a tapered cone to increase the frictional forces (now adjustable magnitude) on pads as a function of the stroke. At the end of the stroke, the friction housing is expanded to permit the device to be reset. In another embodiment a bellows device is utilized to generate pressure on tapered surfaces to increase the holding force of friction pads.
None of the foregoing patents illustrate the present invention which provides for a dry or lubricated energy dissipating device. Laboratory tests have indicated that this invention works better lubricated than dry. In addition, none of the previous inventions have a constant load behavior regardless of stroke or shock intensity.